This post will give you full details on how to avoid healing your Pokemon after an unsuccessful raid.
The cooldown period is around 15 minutes. Everybody knows that 9 minutes for cooling down is not enough, and 11 minutes is just the right amount. So we put a bet that 10 minutes is the amount of time that is needed for a raid to cooldown.
It’s better to start the raid, even if you think you cannot win the battle. If you realize this, you must close the app before the battle timer runs out. You can re-open the app at any time, but it is important not to click the gym where the raid occurred. When you open the app, you can notice that none of your Pokemon are injured. In order for all of this to work, you must wait the cooldown period of 10 minutes, plus the time left on the battle timer before clicking the Gym.
After clicking on the gym, it will appear as if you’ve never participated in the battle, so none of your Pokemon will require potions or revives.
If in the middle of the battle, you discover that you do not have enough power to defeat the raid boss, you can also use this trick to avoid using any potions or even revives. Even though you do have to wait for the cooldown timer to expire, this is not a waste of your time.
If you use the re-roll strategy by DH025 on Reddit, any player that will choose to re-roll, won’t have to spend potions or revives on their injured Pokemon.